Correct process information caching and command line retrieval under Windows

[dustin-johnson]

For the most part command line retrieval appears to be broken under Windows. When investigating the issue, I found that process caching also appears a bit suspect, so I tweaked that logic a bit as well. Since the changes are concise, I'll let the diff speak for the details.

[coveralls]

Coverage remained the same at 91.279% when pulling eda4cac on seeq12:bugfix/windows-get-command-line into dc624b0 on oshi:master.

[codecov-io]

Codecov Report

Merging #527 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #527   +/-   ##
=========================================
  Coverage     83.92%   83.92%           
  Complexity      194      194           
=========================================
  Files            28       28           
  Lines          1400     1400           
  Branches        200      200           
=========================================
  Hits           1175     1175           
  Misses          105      105           
  Partials        120      120

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[dbwiddis]

D’oh!